Update minimum Ruby version and gems

[ctubbsii]

• Update minimum Ruby version to at least the version run by ASF infra team on Jekyll builders, so that way we can reduce compatibility surprises when trying to build on stuff substantially newer than what's on ASF's infrastructure
• Do a bundle update

[ctubbsii]

@clambertus confirmed in Slack that the builder is running Ruby 2.7 (I think it's safe to rely on it not going backwards). I don't think any of these gems require anything newer than 2.7, but I won't know for sure until we commit to trigger the site build with the changes.

Maybe we can add a matrix build for GitHub Actions that tests 2.7 and also 3.3, and we can update the Dockerfile to use 3.3? I'm not sure what's useful to test here. At a certain point, it's probably overkill.

What I do know is these updated gems work fine on Ruby 3.3.0 on my Fedora 40 dev machine. I imagine they work fine with the 3.2.2 version used by our Docker container for testing locally, but I can't test that, since I don't have Docker set up locally. Maybe @ddanielr or @DomGarguilo has that set up already and can test it?